In various industries, continuous monitoring of tension in a web which may be moving at high speed is essential to avoid damage to the web or to maintain proper manufacturing controls on web-supported products. For example, in the manufacture of paper, endless webs are frequently used, and if tension is insufficient, the web tends to wrinkle, forming irregularities in the material being carried by the web. Conversely, if tension becomes too great, the web or product may be weakened or destroyed. In many other applications, such as printing and textile manufacturing, it is necessary to continuously observe and make necessary adjustments to maintain tension on a web within suitable limits.
Numerous systems have been devised for such tension monitoring. One such system is exemplified in U.S. Pat. No. 3,260,106, in which the web is passed over a guide roll and exerts displacing forces upon that guide roll. The guide roll is mounted for rotation upon a support shaft, and the force exerted by the tensioned web upon the guide roll causes deflection of the support shaft which is sensed by a strain gauge or gauges.